title: Assessment of the performances of AcuStar HIT and the combination with heparin-induced multiple electrode aggregometry: a retrospective study.
abstract: BACKGROUND
  Early diagnosis of immune heparin-induced thrombocytopenia (HIT) is challenging. HemosIL® AcuStar HIT and heparin-induced multiple electrode aggregometry (HIMEA) were recently proposed as rapid diagnostic methods.
  
  
  OBJECTIVE
  We conducted a study to assess performances of AcuStar HIT-IgG (PF4-H) and AcuStar HIT-Ab (PF4-H). The secondary objective was to compare the performances of the combination of Acustar HIT and HIMEA with standardised clinical diagnosis.
  
  
  METHODS
  Sera of 104 suspected HIT patients were retrospectively tested with AcuStar HIT. HIMEA was performed on available sera (n=81). The clinical diagnosis was established by analysing in a standardized manner the patient's medical records. These tests were also compared with PF4-Enhanced®, LTA, and SRA in subsets of patients. Thresholds were determined using ROC curve analysis with clinical outcome as reference.
  
  
  RESULTS
  Using the recommended thresholds (1.00AU), the negative predictive value (NPV) of HIT-IgG and HIT-Ab were 100.0% (95% CI: 95.9%-100.0% and 95.7%-100.0%). The positive predictive value (PPV) were 64.3% (95% CI: 35.1%-87.2.2%) and 45.0% (95% CI: 23.2%-68.6%), respectively. Using our thresholds (HIT-IgG: 2.89AU, HIT-Ab: 9.41AU), NPV of HIT-IgG and HIT-Ab were 100.0% (95% CI: 96.0%-100.0% and 96.1%-100.0%). PPV were 75.0% (95% CI: 42.7%-94.5%) and 81.8% (95% CI: 48.3%-97.7%), respectively. Of the 79 patients with a medium-high pretest probability score, 67 were negative using HIT-IgG (PF4-H) test at our thresholds. HIMEA was performed on HIT-IgG positive patients. Using this combination, only one patient on 79 was incorrectly diagnosed.
  
  
  CONCLUSIONS
  Acustar HIT showed good performances to exclude the diagnosis of HIT. Combination with HIMEA improves PPV.
authors.affiliation: Department of Pharmacy, Namur Research Institute for LIfe Sciences (NARILIS), Namur Thrombosis and Hemostasis Center (NTHC), University of Namur, Namur, Belgium. Electronic address: valentine.minet@unamur.be.
authors.forename: V
authors.initials: V
authors.lastname: Minet
authors.forename: N
authors.initials: N
authors.lastname: Bailly
authors.forename: J
authors.initials: J
authors.lastname: Douxfils
authors.forename: J C
authors.initials: JC
authors.lastname: Osselaer
authors.forename: J
authors.initials: J
authors.lastname: Laloy
authors.forename: C
authors.initials: C
authors.lastname: Chatelain
authors.forename: I
authors.initials: I
authors.lastname: Elalamy
authors.forename: B
authors.initials: B
authors.lastname: Chatelain
authors.forename: J M
authors.initials: JM
authors.lastname: Dogné
authors.forename: F
authors.initials: F
authors.lastname: Mullier
mesh_terms: D000328:Adult; D000368:Aged; D001331:Automation; D016022:Case-Control Studies; D004566:Electrodes; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006493:Heparin / Q000009:adverse effects* / Q000276:immunology; D006801:Humans; D008163:Luminescent Measurements / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects* / Q000502:physiology; D010979:Platelet Function Tests / Q000379:methods*; D012189:Retrospective Studies; D013921:Thrombocytopenia / Q000097:blood / Q000139:chemically induced* / Q000175:diagnosis* / Q000276:immunology
chemical_list: D006493:Heparin
keywords: Heparin-induced thrombocytopenia; Immunoassay; Platelets